A Design of Dual-Frequency Dual-Sense Circularly-Polarized Slot Antenna

A single-feed dual-frequency dual-sense circularly-polarized (CP) printed slot antenna etched on a single substrate is proposed. This antenna is composed of an annular slot and a cross slot, which produce two different frequency bands. The lower band and the upper band are controlled by the annular slot and the cross slot respectively. By introducing asymmetry on both annular slot and cross slot, CP radiation at the two frequencies can be obtained. The method of impedance matching has been discussed in detail. The key parameters of the design are investigated to show how to obtain dual-frequency and dual circular polarization. Two antenna prototypes are fabricated and measured, experimental results show that good CP radiation performances are obtained at both frequencies.